Method of processing solvent-ex



Patented July 17, 1951 UNITED STATES ATENT OFFICE John D. Bartleson, East Cleveland, Ohio, assignor to The Standard Oil Company, Cleveland, Ohio, a corporation of Ohio No Drawing. Application May 29, 1948, Serial No. 30,206

8 Claims. 1

This invention relates to processes of improving hydrocarbon base lubricants, and more particularly to the treatment of hydrocarbon lubricants with a small amount of phosphorus pentasulfide followed by the treatment thereof with a base, especially a metal base, to form lubricants having improved properties, especially as to corrosion, lacquer, sludge, viscosity increase, and the like characteristics. It also relates to the resulting improved lubricants, especially those having an ash content.

Many of the commercially used lubricants are formed from hydrocarbon base stocks, which may be synthetically prepared or which may be deture, the amount of sulfide that is to react, the subdivision of the reactants, the efiiciency of mixing the reactants, and the like.

The solvent-refined hydrocarbon lubricant stock is reacted with the phosphorus pentasulfide in a ratio of from about 0.1 to about 0.75% by weight, based on the Weight of the hydrocarbon lubricating base stock, desirably about 0.25 to about 0.60%, and preferably about 0.35 to about 0.5%. Higher amounts of the pentasulfide give products which are inferior to the hydrocarbon as to viscosity increase. Generally, at least about 0.1 thereof should be used to achieve the desired result, although smaller amounts show some imrived from natural sources, such as petroleum. provement. For a y purp es oal ed ad must be The refining of the solvent-refined hydrocarincluded with the hydrocarbon base stock in order hen tock with the phosphorus pentasulfide may 0 p e a lubricant having desirable characbe carried out in the presence or absence of air, teristics, particularly detergency. The solvent or in an atmosphere of inert or non-deleterious gig g 2 55 gi g l zgi g fd gi gge gg i gas, such as nitrogen or HZS. It may also be c gar Y ried out under ressure, e. ressure enera e parted, two additives or a multifunctional addiwhen t t z is carriefi in elgosed tive is required. Generally, the addition of these additives is associated with a higher cost of the The fining temperature varies t t finished lubricant. The preparation of a finished d'rocarbon Steele Genemuy, t temperature 0f tl ifiiicfiifiiihiijti harass. or of w re;r gr tt be at eas 275 F., u s ou e e ow e emf Wanted properties at a Q perature at which the reaction product would be clally interesting cost has been a particularly decomposed. A temperature in the range f i i -$21 32; v crit l i tl i invention it has been about 300 to about 450 R f preferred 1 many cases. The final refined oi is preferaby cenfolnd g i lubn' trifuged or filtered to remove any by-products, humans... is ge g I I with a base, and the resulting reaction product is ig g f 1S LS6 1 may 8 remove y evap an improved lubricant; i. e., a chemically finished The sulfide refined on stock is treated with a or refined lubricant. Such lubricants are suitable has,a derivative Such as a metal Compound The for use under various conditions, including high megal deriVati{,,3s may be formed from one or temperatures or high pressures or both; as, for more metal compounds Such as their sulfides instarirce, use in an internal combustion engine 40 Oxides hydroxides cdlfbides and cyanamides opera ing a high temperatures and in which the lubricant is in close contact with metallic sur- The preferred llnetals are 9 group H and faces, metal compounds and high temperature group s the penodlc.table Such. as

otasslum zinc barium and aluminum especialgases. They are also suitable for use in extreme k t 1 pressure lubricants, e. g., in oils and greases conw 1 a a1 M116 h meta b 01 taming the Sana partlcular services, the heavier metals have par The reaction of the solvent refined hydrocar ticular use, 1. e., those below z1nc 1n the electrobon base stock with the phosphorus pentasulfide motlve $1195, ch as um, cadmlum, t1n, may be conducted with direct admixture of the lead: antlmony, blsmuth arsemc, and the reactants, or, if desired, by their admixture i In the treatment with the base derivatives, the the presence of a diluent which may be subsetreating step may be a r d O t a temperatures quently removed. Generally a diluent is not n the range of about to about 350 F., a temnecessary. The reaction is usually complete in perature in the range of about 180 to 250 F. beabout 10 hours or less time, generally 1 to 2 hours. ing preferred, if the sulfide refined stock has The reaction time is a function of the tempera 5 been subjected to a temperature ofat least 300 Alternatively, the derivative may be prepared at or subjected to this temperature.

From about .25 to about 0.6 equivalents of the metal compound may be used per mol of the sulfide used in the sulfide refined stock, preferably about 1.0 to about 3.0 equivalents. An equivalent is the quotient of a mol divided by the valence of the metal concerned.

The hydrocarbon lubricant stock to which the process is applied is a solvent-extracted or solvent refined oil, i. e., oils treated in accordance with conventional modern methods of solvent refining lubricating oils. The oil may be a fiuid hydrocarbon lubricating base stock having a viscosity at 100 F. of to 500 centistokes, such as used as the base for the S. A. E. 10 to 50 oils. It may be obtained as a distillate or from synthetic material, such as petroleum, and oils produced by cracking, polymerization, hydrogenation, and the like methods. The solvent refining process is well-known, and generally involves a physical separation. Usually, the solvent selected, such as furfural, phenol, sulfur dioxide, etc., dissolves such constitutents as aromatic, unsaturated, and low viscosity index materials, and these are separated out. A clay treatment may or may not follow and is desirable but not essential. Where necessary; a' separate propane or the like deasphalting treatment may be used in connection with the solvent refining.

In order to illustrate and point out some of the advantagesofthe invention, but in no sense as a limitation thereof, the following specific embodiments are included.

In these examples, the hydrocarbon stock is a conventional solvent-extracted or refined lubricating oil base stock, prepared by solvent extracting the raw lubricating oil, and then treating the solvent extracted oil with 8 lbs. of clay per barrel of oil, in a conventional manner. This is a good grade of solvent refined oilavailable on-the market and is typical of such an oil.

The phosphorus pentasulfide is mixed with the hydrocarbon lubricating oil, in the amounts indicated in the following table, and agitated for 1' hour at' 300 F. at atmospheric pressure. Then it is mixed withthe amount and kind of base indicatedin the following table, and agitated for 2' hours at 250 F. and at atmospheric pressure. The base used for convenience is in anyhydrous form, but may be in aqueous solution if desired. A good yield is obtained, based on the hydrocarbonlubricating oil, and no sludge is formed; but it ispreferred to filter the reaction product. The

reaction product is identified hereinafter by the example number.

Amount of P185 in Per Example Cent by Amount of Base (Relative to Ash Number Weight of Weight of Hydrocarbon Hydrocarbon Per cent 0.4 0.2% KOH O. 27 0. 4 0. 4 0.30 0. 4 0. 0. 49 0. 4 0. 0.40 0.4 0. 0. 026 0.4 0 0. 097 0. 4 0 0. 105 0. 4 0 0. l4 0. 4 0 0. 025

The Sohio corrosion test was used in evaluating lubricants made in accordance with the invention. This test is described in a co-pending application of E. C. Hughes, J. D. Bartleson, M. L. Sunday and M. M. Fink, which also correlates the results of the laboratory tests with a Chevrolet engine test.

Essentially the laboratory test equipment consists of a vertical thermostatically heated glass test tube (45 mm. outside diameter and 42 cm. long), into which is placed the corrosion test unit. An air inlet is provided for admitting air into the lower end of the corrosion unit in such a way that in rising the air will cause the oil and suspended material therein to circulate into the corrosion unit. The tube is filled with an amount of the oil to be tested which is at least sufilcient to submerge the metals being tested.

The corrosion test unit essentially consists in a circular relatively fine grained copper-lead test piece of -l?' O. D., which has a diameter hole in its center (i. e., shaped like an ordinary washer). The testpiece has an exposed copperlead surface of 3.00 sq. cm. Of this surface area, 1.85 sq. cm. acts as a loaded bearing, and is contact'ed" by a part of the cylindrical surface of a hardened steel drill rod (14 diameter and fie" long, and of 51-57 Rockwell hardness).

The drill rod is held in a special holder, and the holder is rotated so that the surface of the drill rod which contacts the bearing sweeps the bearingsurface (the drill rod is not rotated on its own axis and the surface of the drill rod which contacts the bearing is not changed).

The corrosion test unit means for holding the bearing andthe drill rod is a steel tubing (15" lon'gand lse O. D.) which is attached to a supp'orti A steel cup (1" long, lfi g" O. D. by 1% I. D.) isthreaded into the steel tube, at the lower end; The'cup has a 7 diameter hole in the bottom for admitting the Oil into the corrosion chamber. The copper-lead test piece fits snugly intothe steel cup and the hole in the test piece fitsove'r the hole in the steel cup. A section of steel'rod in diameter and 19" long) serves as a shaft and is positioned by 2 bearings which are fixedly set in the outer steel tubing, one near the top and one near the lower (threaded) end thereof. Several holes are drilled just above and just below the lower bearing. the bearing facilitate cleaning the apparatus, while the holes below the bearing enable the circulation of oil through the corrosion chamber. The drill rod holder is connected to the shaft by aself-aligning yoke and pin coupling. This assur es instantaneous and continuous alignment of ofthe'shaft and attached members is about 600- grams, which is the gravitational force which represents the thrust on the bearing. The air lift from the air inlet pumps the oil through the chamber containing the test piece and out through the holes in the steel tubing.

The ratios of surface active metals to the volumeofoil in an internal combustion test engine are nearl quantitativel duplicated in the test equipment. The temperature used is approximately that of the bearing surface. The rate of air flow per volume of oil is adjusted to the same as the average for a test engine in operation. Of the catalytic effects, those due to soluble ironare the'most important. They are empirically duplicated by the addition of a soluble iron-salt. Those The holes above due to lead-bromide are duplicated by its addition.

The test was correlated with the LA Chevrolet test, and a slightly modified version thereof. The modified test comprised reducing the oil additions from the 4 quarts in the usual procedure to 2 quarts, by reducing the usual 1 pint oil additions which are made at 4 hour intervalsto /2 pint additions. This modification increases the severity of the test in its corrosion and detergency components, particularly in the case of border line oils.

For each test, the glass parts are cleaned by the usual chromic acid method, rinsed and dried. The metal parts are washed with chloroform and carbon disulfide and polished with No. 925 emery cloth or steel wool. A new copper-lead test piece is used for every test. The test iece is polished before use, on a Surface grinder to give it a smooth finish. The test piece is weighed before and after the test on an analytical balance to evaluate the corrosion. After placing the oil and corrosion test unit inthe tube, and bringing the as sembly up to temperature in the thermostat, soluble catalyst is added and the air flow is started. Lead-bromide catalyst is added immediately after starting the air, and timing of the test is begun.

The laboratory test conditions which were found to correlate with the Chevrolet procedure 36-hour test are shown in the following table:

Table A Temperature325 F. Oil sample'7 cc. Air flow rate-'70 liters/ hour Time10 hours CatalystsSteel; copper-lead bearing: 3 sq. cm. area of which 1.85 sq. cm. is a bearing surface; ferric Z-ethyl hexoate: 0.05% as Fe2O3 in C. P. benzene; lead bromide: 0.1% as precipitated powder. Bearing assembly:

Load grams; 600 Speed R. P. M 675 By extending the laboratory test to hours, it was found that correlation with the Chevrolet 72-hour test could be obtained.

At the close of the test period, the extent of corrosion is determined by reweighing the corrosion test piece and determining the change in weight due to the test. An accurate evaluation of the lacquering properties of an oil is obtained by a visual rating system which is applied to the outer surface of the corrosion unit steel tube and metal cup in much the same way that the piston skirt, cylinder wall, etc., of an engine are rated for varnishes. The sludge rating of the engine is simulated by a visual rating of the insoluble materials and used oil which are coated on the glasstest tube of the conclusion of the test. For both sludge and varnish rating a scale rating of A (best) to F (worst) is used.

A sufficient volume of used oil is obtained from the test for determination of the usual used oil properties, such as pentane insolubles (sludge), viscosity increase, neutralization number and optical density.

The data in the following tables typify the results obtained in 20-hour Sohio corrosion tests on the hydrocarbon lubricating oil base stock, and the improved lubricants prepared therefrom in accordance with the invention.

Table I LubricantExa-mple No mghgy 1 2 3 4 Corrosion of Cu-Pb (in mgms.

Wt. loss of) 40.1 3. 5 16.3 13. 3 6. 8 Viscosity Increase (SUS) 4, 070 19 152 72 108 Pentane Insolubles (in mgm 10 g. of lubricant) 25. 8 5. 0 2. 6 9. 5 8. 9 Acid Number 11.3 0.7 1.9 0.71 1.0 Sludge Rating... A- A+ A- A+ A+ Lacquer Rating A A A+ A A Table II S. E. LubricantExample No Oil 5 6 7 8 9 (blank) Corrosion of Cu-Pb (in mgms. wt. loss of) 40. l 39. 7 19.5 12. 5 9. 9 41. 0 Viscosity Increase (SUS) 4, 070 464 218 163 149 947 Pentane Insolubles (in mgn1./l0 g. of lubricant) 25.8 1. 66 1.01 1. 04 0. 24 4. (i3 Acid Number. ll. 3 l. 5 1.6 2. 6 l. 1 3. 2 Sludge Rating A- A- A A- A B Lacquer Rating. A O O C O C The ash content is important in these lubricants, since it is associated with good detergency. As to this feature, the ratio of the sulfide to the base used in Example 3 is particularly advan tageous.

In preparing the metal derivative of Example 1, the base is used in dry form. In a similar run, except using the same amount of base in aqueous solution, a desirable lubricant is obtained. However, the lubricant of Example 1 shows better corrosion, viscosity increase, acid number, sludge and optical density characteristics. This indicates that an aqueous base may be used but that a dry base is much to be preferred.

In runs comparable to those of the foregoing examples, except using 0.4% and 0.1%, respectively, of P482. as the sulfide, it is found that the treatment with the base has the effect of taking substantially all the P483 out of the oil, i. e., giving a product of substantially zero ash content.

In a run similar to Example 2, except using raw #300 Red Oil (a conventional Mid-Continent lubricating oil stock, of 20-30 S. 'A. E. Viscosity) a product having an ash content of 0.22% is obtained. It is inferior to the Example 2 reac tion product as to corrosion, viscosity increase, acid number, pentane insolubles, sludge, and lacquer characteristics. This indicates that for the requisite detergency, the oil should be solvent refined before treatment with phosphorus sulfide.

The 36-hour L-4 Chevrolet engine test was also used in comparing the oils of Examples 3 and 4. In this test, new piston rings and two new copper-lead bearing inserts are installed in the motor prior to each test. The engine is a conventional Chevrolet engine with 216.5 cu. in. piston displacement and a compression ratio of 6.5 to 1. The engine is operated at 3150 R. P. M. with a load of 30 B. H. P. and at a temperature at the jacket outlet of 200 F. The lubricating oil temperature is maintained at 265 F. for an S. A. E. 10 grade oil, and at 280 F. for oils of S. A. E. 30 to 50 grades. The fuel used contains from 2.5 to 3.0 ml. tetra-ethyl lead per gallon. Besides the Weight loss of the test bearings, deposits in the power section, and properties of the used oil, sampled near the middle and also at the end of the test, are examined. The following results were obtained:

Table III LubricantExample No u S. E. Oil l 3 4 These I'able III Chevrolet test data also show i that the amount of the metal is not particularly 1' critical and further tests show that increasing .the amount of metal does not have any effect 1 (good or bad) on the oil. Other tests show that the amount of P285 used in the examples is opti- ::mum and amounts above and below this within \ithe'range disclosed heretofore, while yielding an improvement on the untreated oil gives somewhat higher corrosion and viscosity increase than *the optimum.

The greatly improved corrosion characteristic :'in the chemically refined or finished lubricants, particularly with detergency, is especially note- 'worthy, since this is a major problem with conxventional solvent refined oils.

By comparable procedures, using any known comparable phosphorus sulfide, or any amount of phosphorus sulfide, or any hydrocarbon lubricating oil stock, coming within the broad types and ranges as indicated hereinbefore, comparable improved lubricants are obtained.

If desired, the improved lubricants of the invention may be used in blends together with other lubricants or lubricant agents, e. g., with soap or the like in a grease. If desired, an agent for improving the clarity of the oil may be included, e. g., lecithin, lauryl alcohol, and the like. If desired, an agent for preventing foaming may be included, e. g., tetra-amyl silicate, an alkyl ortho-carbonate, ortho-formate or ortho-acetate, or a polyalkyl silicone oil.

In View of the foregoing disclosure, variations and modifications of the invention will be apparent to those skilled in the art, and it is intended to claim such variations and modifications broadly, except as do not come within the scope of the appended claims.

I claim:

1. A method of further processing solvent-extracted lubricating oil stock consisting essentially of hydrocarbon material to yield an oil having improved inhibition to oxidation in service, which method comprises treating said stock with an amount of phosphorus pentasulfide in the range of about 0.1 to about 0.75% by weight at a temperature in the range of about 275 to 450 F., and then with an amount of a base in the range of about 0.25 to 6.0 equivalents per mol of the phosphorus pentasulfide.

2. The method of claim 1 wherein the stock is treated with an amount of phosphorus pentasulfide in the range of about 0.25 to about 0.6% at a temperature in the range of about 300 to 450 F., and then with an amount of a metal base in the range of about 1.0 to about 6.0 equivalents per mol of the phosphorus pentasulfide.

3. The method of claim 2 wherein the stock is treated with an amount of phosphorus pentasulfide in the range of about 0.35 to about 0.5%, and then with an amount of potassium hydroxide in the range of about 1 to about 3.0 equivalents per mol of the phosphorus pentasulfide.

4. The method of claim 3 wherein the stock is a clay-treated stock, and wherein said stock is treated with about 0.4% of phosphorus pentasulfide, and then with an amount of dry potassium hydroxide in the range of about 0.6 to about 0.8% by weight of the stock.

5. A lubricant obtained by the claim 1.

6. A lubricant claim 2.

7. A lubricant claim 3.

8. A lubricant claim 4.

process of obtained by the process of obtained by the process of obtained by the process of JOHN D. BARTLESON.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 2,316,091 White Apr. 6, 1943 2,393,335 Musselman Jan. 22, 1946 2,398,429 Hughes Apr. 16, 1946 2,419,584 Noland Apr. 29, 1947 Certificate of Correction July 17, 1951 Patent No. 2,560,546

JOHN D. BARTLESON certified that error appears in the printed specification of d patent requiring correction as follows:

strike out further and that the said Letters Patent should be tea the same may conform to the record of the case in Signed and sealed this 13th day of November, A.

It is hereby the above numbere Coh1mn7 line 50,

so that d. as oorrected above,

the Patent Oflice.

THOMAS F. MURPH Assistant Gem/mission of Patents. 

1. A METHOD OF FURTHER PROCESSING SOLVENT-EXTRACTED LUBRICATING OIL STOCK CONSISTING ESSENTIALLY OF HYDROCARBON MATERIAL TO YIELD AN OIL HAVING IMPROVED INHIBITION TO OXIDATION IN SERICE, WHICH METHOD COMPRISES TREATING SAID STOCK WITH AN AMOUNT OF PHOSPHORUS PENTASULFIDE IN THE RANGE OF ABOUT 0.1 TO ABOUT 0.75% BY WEIGHT AT A TEMPERATURE IN THE RANGE OF ABOUT 275* TO 450* F., AND THEN WITH AN AMOUNT OF A BASE IN THE RANGE OF ABOUT 0.25 TO 6.0 EQUIVALENTS PER MOL OF THE PHOSPHORUS PENTASULFIDE.
 5. A LUBRICANT OBTAINED BY THE PROCESS OF CLAIM
 1. 